Check valve



FIG. 1 is a perspective view of a check valve showing my new design;

FIG. 2 is a side elevation view thereof;

FIG. 3 is a front elevation view thereof; and,

FIG. 4 is a rear elevation view thereof, shown in larger scale.

The broken lines showing of elements within the outer cylindrical sleeve in FIG. 4 are for the purpose of illustrating portions of the check valve and form no part of the claimed design. 

CLAIM The ornamental design for a check valve, as shown and described. 